Combining ability analysis over environments for fibre characters in upland cotton

In an 8 x 8 parent diallel cross of G. hirsutum L. evaluated in 3 environments, additive type of gene action was preponderant for ginning percentage, seed index, lint index, 2.5% span length and fibre fineness. Interaction effects of GCA and SCA with environments were highly significant for all the characters except ginning percentage and 2.5% span length respectively. The GCA effects were more stable over a range of environments, whereas the SCA affecs were much influenced by environmental variation for the traits. Parent, LRK-516 found to be good general combiner for all the characters, while G.Cot. 10 also found to be a good general combiner for all the characters except fibre fineness. Cross combinatiions G.Cot.10 x B.N. and G. 2360 x LRK-516 gave high SCA effects for seed index, lint index and 2.5% span length, while crosses H 777 x DCI - 108 and Sharda x G. 2360 for ginning percentage, seed index and lint index.